RFR: 8334397: RISC-V: verify perf of ReverseBytesS/US

[Ludovic Henry]

On Fri, 21 Jun 2024 14:24:26 GMT, Hamlin Li <mli at openjdk.org> wrote:

> Hi,
> Can you help to review this patch?
> Thanks!
> 
> This is similar with previous JDK-8334396.
> Added some tests.
> 
> ### Test
> <google-sheets-html-origin style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
>   | Tests | Scores | Errors | Unit
> -- | -- | -- | -- | --
> Intrinsic, +zbb, +rvv | Characters.reverseBytes | 1654.535 | 69.36 | ns/op
>   | Shorts.reverseBytes | 1795.403 | 44.015 | ns/op
> Intrinsic, +zbb, -rvv | Characters.reverseBytes | 1649.752 | 74.965 | ns/op
>   | Shorts.reverseBytes | 1798.637 | 49.52 | ns/op
> Intrinsic, -zbb, +rvv | Characters.reverseBytes | 2279.588 | 44.222 | ns/op
>   | Shorts.reverseBytes | 2441.674 | 63.895 | ns/op
> Intrinsic, -zbb, -rvv | Characters.reverseBytes | 2288.876 | 49.099 | ns/op
>   | Shorts.reverseBytes | 2454.454 | 94.004 | ns/op
> No intrinsic | Characters.reverseBytes | 1629.722 | 23.656 | ns/op
>   | Shorts.reverseBytes | 2108.81 | 43.378 | ns/op
> 
> </google-sheets-html-origin>

test/micro/org/openjdk/bench/java/lang/Characters.java line 69:

> 67: 
> 68:     @Benchmark
> 69:     public void reverseBytes() {

I'm not sure we want to be adding that benchmark to this class. Could you move to a different class that will test exclusively `reverseBytes` on `char[]`? You can then move the code from `test/micro/org/openjdk/bench/java/lang/Shorts.java` into that same class or a similarly named class for `short[]`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19830#discussion_r1651605527